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Abstract:

A management server has: a terminal state management unit that manages
state information transmitted from information terminals and including
information on an information terminal and a user associated with each
information terminal; and a network configuration management unit that
selects adjacent information terminals of each information terminal based
on the state information of each information terminal managed by the
terminal state management unit, and calculates a connection link, which
is a network for interconnecting adjacent information terminals, wherein
the information terminal has: an internal state management unit that
manages the state information of the information terminal; an adjacent
management unit that manages information on adjacent information
terminals selected by the network configuration management unit; and a
messaging unit that stores a message acquired from an adjacent
information terminal via the connection link and a message inputted by
the user in a message box opened to the other information terminals, and
manages these messages, and the network configuration management unit
calculates a degree of dissimilarity among information terminals based on
the state information of each information terminal, and calculates a
first type connection link that creates a connection link sequentially
from an information terminal having a lower degree of dissimilarity, and
a second type connection link which is created stochastically based on
the degree of dissimilarity.

Claims:

1. A coordinated information collection system comprising a management
server and a plurality of information terminals which are connected via a
communication network, wherein the management server has: a terminal
state management unit that manages state information transmitted from the
information terminals and including information on an information
terminal and a user associated with each of the information terminals;
and a network configuration management unit that selects adjacent
information terminals of the information terminals, based on the state
information of each of the information terminals managed by the terminal
state management unit, and calculates a connection link, which is a
network for interconnecting the adjacent information terminals, and the
information terminals respectively have: an internal state management
unit that manages the state information of the information terminal; an
adjacent management unit that manages information on adjacent information
terminals selected by the network configuration management unit; and a
messaging unit that stores a message acquired from an adjacent
information terminal via the connection link and a message inputted by
the user in a message box opened to other information terminals, and
manages these messages, and wherein the network configuration management
unit calculates a degree of dissimilarity among information terminals
based on the state information of each information terminal, and
calculates a first type connection link that creates a connection link
sequentially from an information terminal having a lowest degree of
dissimilarity, and a second type connection link which is created
stochastically based on the degree of dissimilarity.

2. The coordinated information collection system according to claim 1,
further comprising: an information management unit that analyzes a
message acquired from another information terminal via the connection
link; and an action algorithm unit that executes predetermined processing
using a message analysis result by the information management unit.

3. The coordinated information collection system according to claim 1,
wherein the internal state management unit acquires and manages a current
position measured by GPS as the state information, and the degree of
dissimilarity is calculated from relative positions among information
terminals based on the current positions.

4. The coordinated information collection system according to claim 1,
wherein the second type connection link is generated with a similar
probability regardless the degree of dissimilarity, and when the degree
of dissimilarity with an information terminal other than an information
terminal connected via the first type connection link is r, a probability
that the second type connection link is created with this information
terminal is in proportion to the -.alpha.th power of r (α is a
positive number).

5. The coordinated information collection system according to claim 1,
wherein the messaging unit sequentially stores a new message, which is
periodically acquired via the first type connection link or the second
type connection link, in the message box, when the storage capacity of
the message box reaches the upper limit, the messaging unit discards the
oldest message among the messages on a same target as a new message from
among the stored messages, and when there are no messages on a same
target as a new message, the messaging unit discards the oldest message
among all the stored messages, and stores the new message, and discards
as well a message of which storage period is not less than a
predetermined time or a message acquired via a predetermined number or
more information terminals.

6. The coordinated information collection system according to claim 2,
wherein the message is on target witness information, including a
position where a target has been witnessed, and the action algorithm unit
outputs a message of which generation time is the latest, until the
distance between the current terminal and the target becomes a
predetermined distance or less.

7. The coordinated information collection system according to claim 2,
wherein the message is on target witness information, including a
position where the target has been witnessed, and the action algorithm
unit outputs a message of which generation time is the latest until the
current terminal arrives at the destination.

8. The coordinated information collection system according to claim 2,
wherein the state information is a value that indicates content
characteristics of a web page which the user is browsing or has browsed
using the information terminal, the degree of dissimilarity reflects a
degree of dissimilarity of content characteristics of any two web pages,
the message contains information on the content of a web page, and the
action algorithm unit blocks accessing a harmful Web page according to
predetermined conditions, using a message analysis result.

9. A coordinated information collection method used for a coordinated
information collection system having a management server and a plurality
of information terminals which are connected via a communication network,
wherein the management server manages state information, associated with
each of the information terminals and transmitted from the information
terminal, and selects adjacent information terminals of each information
terminal based on the state information of each of the information
terminals, and calculates a connection link, which is a network for
interconnecting adjacent information terminals, and the information
terminal stores a message acquired from an adjacent information terminal
via the connection link, and a message inputted by the user in a message
box opened to other information terminals, and manages these messages,
and the connection link includes a first type connection link that
creates a connection link sequentially from an information terminal
having a lowest degree of dissimilarity, among information terminals,
which is calculated based on the state information of each information
terminal, and a second type connection link which is created
stochastically based on the degree of dissimilarity.

10. A program for causing a computer to function as: a terminal state
management unit that manages state information transmitted from a
plurality of information terminals and including information on an
information terminal and a user associated with each of the information
terminals; and a network configuration management unit that selects
adjacent information terminals of the information terminals, based on the
state information of each of the information terminals managed by the
terminal state management unit, and calculates a connection link, which
is a network for interconnecting the adjacent information terminals,
wherein the network configuration management unit calculates a degree of
dissimilarity among information terminals based on the state information
of each of the information terminals, and calculates a first type
connection link that creates a connection link sequentially from an
information terminal having a lowest degree of dissimilarity, and a
second type connection link which is created stochastically based on the
degree of dissimilarity.

Description:

BACKGROUND

[0001] The present invention relates to a coordinated information
collection system, a coordinated information collection method, and a
program.

[0002] In a dynamic large scale system of which state constantly changes,
it is difficult to collect and process events which occur at an
unpredictable timing and place with a good real-time method. An available
method commonly known is a method of collecting information constantly
and intensively in the background. For example, by searching a web page,
information is always being collected and updated, and an enormous volume
of collected information is organized by visiting web pages distributed
throughout the Internet using a program called a "crawler". However as
the scale of processing increases, the method of managing all events
intensively cannot keep up with demand, and real-time processing
corresponding to the dynamic changes becomes difficult. An effective
method for processing events in real-time in a large scale system is a
distributed processing method. One such method is to utilize a social
network, which is a network of individuals, that is, constituting the
network by composing elements distributed in the system.

[0003] Non-patent Document 1 describes a contest where red balloons are
set at ten places in the United States, and a team that identifies all
the places first wins the contest. The MIT Media Lab Team won this
contest, using a recursive recruiting method modeled by following a
social network of individuals distributed nation-wide, and rewarding a
participant who reported a correct position of a balloon. In other words,
each distributed individual, which is a composing element of a network,
searched target information (place of a balloon) recursively using only
local information (adjacent nodes of this individual), such as k number
of friends of this individual, and k number of friends of each of these
friends . . . , and identifies all the places of the balloons in a short
time of 8 hours 52 minutes. This is an effective method to collect
distributed information by "human sensors" distributed nation-wide as
much as possible when there is no prior knowledge on the positions of the
balloons, even if network resources are consumed.

[0004] In a case when a relationship between a characteristic of a search
target and a characteristic of a configuration node of a network can be
specified, it is known that an efficient method can be implemented by
using a similarity of the characteristics, which is better than
broadcasting a query. For searching data, to include files as well, many
efficient methods for searching target information by creating a network
based on similarity and tracking the network have been proposed. For
example, a characteristic of data is represented by a point in an
appropriate characteristic space, and a network is constructed based on a
distance of an arbitrary two datum. Search is performed by repeating
processing to advance to a node which is likely closest to a search
target data among adjacent nodes connected to each node, and if a
searchable network structure is constructed, efficient searching becomes
possible merely by going through limited nodes.

[0006] The conventional methods, including the method described in
Non-patent Document 1, are all distributed search methods utilizing only
local adjacent information of distributed nodes. According to these
methods, if a structure (connection structure of the network) of the
distributed nodes, based on positional relationships in a space where the
characteristics thereof are mapped, is created in advance, then a node
closely related to the search target event can be searched by efficiently
tracking the network using a relationship of the characteristic of the
search target event and the characteristic of the network node as a clue.
If this clue is not available, a node closely related to the search event
is searched by recursively expanding the search to the adjacent nodes
sequentially from the start node using the network, and in order to
decrease search time, the number of search nodes is increased by
broadcasting, which consumes network resources.

[0007] A problem of this method is the case when a distributed search
using a network is performed for an event of which location in the system
is unpredictable, and if a relationship between the characteristic of the
event and the characteristic of the network node is not clearly
specified, consumption of network resources for search increases. This is
because a direction in the network, where the node having detailed
information on the search target event exists, is unknown, and with a
query being broadcasted reclusively not for specific adjacent nodes but
for all the adjacent nodes, network resource consumption increases
explosively every time the number of hops increases.

[0008] Another problem is that in the case of a search that conserves
network resource consumption, search efficiency is greatly different
depending on the network structure, the initial position of the searcher
in the network and the position of the network node having the detailed
information on the search event. This is because in a case when the
number of adjacent nodes to which a query can be broadcasted at once is
decreased in a search of an arbitrary search event, the search can be
quickly completed if the initial position of the searcher happens to be
near the node having the detailed information on the search event, and
the searcher can reach this node with the small number of hops, but if
the user is located very far from the node requiring many hops, then the
probability of reaching the node becomes very low, and search takes a
long time.

SUMMARY

[0009] With the foregoing in view, it is an exemplary object of the
present invention to provide a coordinated information collection system,
and that can search and collect information efficiently in real-time in a
system in which states change dynamically, while keeping consumption of
network resources low.

[0010] A coordinated information collection system according to the
present invention is a coordinated information collection system
comprising a management server and a plurality of information terminals
which are connected via a communication network, wherein the management
server has: a terminal state management unit that manages state
information transmitted from the information terminals and including
information on an information terminal and a user associated with each of
the information terminals; and a network configuration management unit
that selects adjacent information terminals of the information terminals,
based on the state information of each of the information terminals
managed by the terminal state management unit, and calculates a
connection link, which is a network for interconnecting the adjacent
information terminals, and the information terminals respectively have:
an internal state management unit that manages the state information of
the information terminal; an adjacent management unit that manages
information on adjacent information terminals selected by the network
configuration management unit; and a messaging unit that stores a message
acquired from an adjacent information terminal via the connection link
and a message inputted by the user in a message box opened to other
information terminals, and manages these messages, and wherein the
network configuration management unit calculates a degree of
dissimilarity among information terminals based on the state information
of each information terminal, and calculates a first type connection link
that creates a connection link sequentially from an information terminal
having a lowest degree of dissimilarity, and a second type connection
link which is created stochastically based on the degree of
dissimilarity.

[0011] According to an exemplary aspect of the present invention,
information can be searched and collected efficiently in real-time in a
system in which states dynamically change, while keeping consumption of
network resources low.

DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a block diagram depicting a configuration of a
coordinated information collection system according to an embodiment of
the present invention.

[0013] FIG. 2 is a diagram depicting an example of a network structure
according to an embodiment of the present invention.

[0014] FIG. 3 is an example of a terminal state management table according
to an embodiment of the present invention.

[0015]FIG. 4 is a diagram depicting a function of a network configuration
management unit according to an embodiment of the present invention.

[0016]FIG. 5 is a diagram depicting a function of a messaging unit
according to an embodiment of the present invention.

[0017]FIG. 6 is a diagram depicting a propagating state of messages
according to an embodiment of the present invention.

[0018] FIG. 7 is a flow chart depicting an operation of an information
terminal according to an embodiment of the present invention.

[0019]FIG. 8 is a diagram depicting Example 1 of the present invention.

[0020]FIG. 9 is a diagram depicting tracking steps of a tracker according
to Example 1 of the present invention.

[0021] FIG. 10 is a flow chart depicting an operation of the tracker
according to Example 1 of the present invention.

[0022]FIG. 11 is a diagram depicting Example 2 of the present invention.

EXEMPLARY EMBODIMENT

[0023] An exemplary embodiment of the present invention will now be
described with reference to the drawings.

[0024]FIG. 1 is a block diagram depicting a configuration of a
coordinated information collection system according to an embodiment of
the present invention. As FIG. 1 shows, the coordinated information
collection system has a management server 101 and an information terminal
102. The management server 101 and the information terminal 102 are
connected via a network 104. A plurality of information terminals 102 on
the network 104 constitute an information terminal group 103.

[0025] The management server 101 includes a CPU, a ROM, a RAM, a
communication interface and a hard disk device, and operates by the CPU
executing various control programs which are read from such a storage
devices as ROM and hard disk to RAM.

[0026] The management server 101 has a communication unit 121, a terminal
state management unit 122 and a network configuration management unit
123, and each of these components is an operation module which the CPU
executes according to a program.

[0027] The communication unit 121 has a function to execute a network
protocol for performing communication via the network 104. Typically the
protocol is TCP.

[0028] The terminal state management unit 122 has a function to manage
each internal state information (state information) transmitted from the
information terminal 102. The internal state information is a current
position acquired by GPS (Global Positioning System), for example.
Information expressed by vectors may be used instead. The terminal state
management unit 122 is a component to manage information unique to each
information terminal 102 and a user who uses the information terminal,
and is not limited to the above mentioned mode.

[0029] The network configuration management unit 123 has a function to
calculate a network structure to be constituted by the information
terminals 102, and to manage the network based on the internal state of
each information terminal 102 managed by the terminal state management
unit 122. The calculated network information (adjacent information of
each information terminal 102) is transmitted to each information
terminal 102 respectively.

[0030] The information terminal 102 includes a CPU, a ROM, a RAM, a
communication interface and a hard disk device, and operates by the CPU
executing various control programs which are read from such a storage
device as ROM and hard disk to RAM. The information terminal 102 is a
personal computer, a portable telephone, a portable information terminal
or the like.

[0031] The information terminal 102 has a communication unit 111, an
information management unit 112, an internal state management unit 113,
an interface unit 114, an adjacent management unit 115, a messaging unit
116, and an action algorithm unit 117. Each of these components is an
operation module which the CPU executes according to a program.

[0032] The communication unit 111 has a function to execute a network
protocol for performing communication via the network 104. Typically the
protocol is TCP.

[0033] The information management unit 112 manages information inputted by
the user via the interface unit 114. The information management unit 112
also inserts a message inputted by the user into a buffer of the
messaging unit 116. The information management unit 112 also processes
and manages message information acquired from another information
terminal 102 via the managing unit 116.

[0034] The internal state management unit 113 has a function to edit and
manage information on the current state (internal state) of the
information terminal 102 and the user. The internal state is, for
example, a current position acquired by GPS. The internal state may also
be information expressed by vectors, and in this case, the internal state
management unit 113 manages a history of the vectors. Generally the
internal state management unit 113 is a component to manage information
unique to each information terminal 102 and a user who uses the
information terminal, and is not limited to the above mentioned mode.

[0035] The interface unit 114 has an interface function for the user to
input/output information to/from the information terminal 102, and
includes a GUI (Graphical User Interface) or a CLI (Command Line
Interface), for example.

[0036] The adjacent management unit 115 manages information on adjacent
information terminals 102, to which each information terminal 102 is
connected via the network 104. The information is typically a list of IP
addresses and host names of other information terminals 102. The link for
connection may or may not have a direction, but in this embodiment, it is
assumed that a directed link is used. The direction is assumed to be a
direction from another information terminal 102 having a registered IP
address to the current terminal.

[0037] The messaging unit 116 has a function to acquire and buffer
information owned by another information terminal 102 registered in the
adjacent management unit 115 (hereafter called "message"), or to fetch a
message when a message acquisition request is received from another
information terminal 102.

[0038] The action algorithm unit 117 uses an algorithm unit to describe an
action of an information terminal 102 and a user based on information
extracted from message information processed by the information
management unit 112. If only processing onboard the information terminal
102 is performed, the algorithm unit automatically performs predetermined
processing, and if action is prompted to the user, the action algorithm
unit 117 outputs the information to the user via the interface unit 114,
and performs a new action responding to the input or action by the user.

[0039] The network 104 is the Internet, for example, and a network
infrastructure protocol, such as TCP/IP, which allows highly reliable
communication, can be used. Physically the network 104 can be radio or
cable.

[0040] Now the network structure managed by the network configuration
management unit 123 of the management server 101 will be described in
detail with respect to FIG. 2 to FIG. 4. FIG. 2 is a diagram depicting an
example of a network structure, FIG. 3 is an example of a terminal state
management table, and FIG. 4 is a diagram depicting a function of the
network configuration management unit 123.

[0041] Here the internal state of the information terminal 102 is
described using only two-dimensional vectors (the height direction is
ignored), that expresses a geodetic position, but expression of the
internal state is not limited to this, and it is sufficient if a
characteristic of a state of an information terminal 102 is expressed as
one point in a space so that dissimilarity of the state among terminals
can be measured using a distance defined in that space.

[0042] The internal state management unit 113 constantly updates the
internal state of the information terminal 102 using GPS, and transmits
this information to the management server 101. The terminal state
management unit 122 of the management server 101 manages the current
internal state of all the information terminals 102 by the terminal state
management table shown in FIG. 3. In the terminal state management table,
as shown in FIG. 3, an internal state ξi is held for each ID=i of the
information terminal 102.

[0043] The internal state information may be periodically notified from
each information terminal 102 at a predetermined period. Notification may
be sent non-periodically based on a predetermined rule, such as when the
position of the information terminal 102 is moved a predetermined
distance or more. Notification may be sent when a query is received from
the management server 101.

[0044] The management server 101 may manage only the latest internal state
of each information terminal 102, or may manage a past record if
necessary. The network configuration management unit 123 calculates the
adjacency of each information terminal at an appropriate timing, using
the terminal state management table, so as to manage the network
configuration.

[0046] The type 0 adjacent calculation unit 402 selects the k0 number of
nodes in sequence, from a node having a shortest distance (distance
expressed by geodetic coordinates) to each information terminal 102. In
the case of the example shown in FIG. 2, four adjacent nodes (k0=4) are
selected for the node 201, and a node 202, for example, is one of these
four. Here if a typical distance that includes the k0 number of nodes is
selected as a reference distance r0, and an area of which radius is r0 is
specified as an area 210, then all the type 0 adjacent nodes are included
in the area 210. For example, if N number of information terminals 102
are evenly distributed in the circle of which radius is R, R
((k0+1)/N)0.5 can be used as a typical r0.

[0047] Now a method for the type 1 adjacent calculation unit 403 to select
type 1 adjacent nodes will be described. Here it is assumed that in use
of r0 an internal area of a circle of which radius is a distance I from
the node u, that is I=r0×2j (j=0, . . . , j*+1), and a shell
Sj (u) is Sj (u)=(Bj (u))∩Bj+1 (u). Here (A) is
the negation of A. In other words, Sj (u) is an area of which
distance from the node u is greater than r0×2' and smaller than
r0×2j+1. When a node v is a node in a set of nodes of which
distance is longer than r0, that is (B0 (u)), a probability that the
node v will be selected as a type 1 node is given by the following
expression (1).

[0048] Here d (u, v) is a distance between u and v, and α is a
control parameter determined by the number of dimensions D (D=2 in this
example). α is a parameter to determine a distance of a node that
can be linked, and a closer node is selected as a becomes greater.

[0049] If α=κD (1≦κ<2) is used as a typical
value, the type 1 adjacent links from the node u are created to the nodes
belonging to Sj (u) with approximately even probability for all the
values of j, so adjacent nodes are selected with approximately even
probability for all the distance scales from the node u. Therefore a link
will be created with any node, and a message can be received from the
node with an approximately same probability, regardless of the distance
of the distance scale. According to this probability, k1 number of
adjacent nodes are selected.

[0050] For example, in the case of D=2, that is in the case when d (u, v)
is expressed as a distance on a plane, if d (u, v) doubles, an area of
the circle of which radius is d (u, v) quadruples, therefore if nodes are
evenly distributed, the number of nodes existing in the circle also
quadruples. Hence if links are formed based on the same probability, more
links are created with distant nodes, but in the case of Expression (1),
the probability with α=1 is in proportion to the negative second
power of d (u, v), so the link establishing probability when d (u, v) is
large can be kept low. As a consequence, adjacent nodes are selected with
approximately even probability for all the distance scales from the
perspective of node u. This effect is greater as a becomes greater.

[0051] In the case of the example shown in FIG. 2, if the node 201 is the
node u and k1=2, the node 203 is selected from the shell S2 (u) and
the node 204 is selected from the shell S3 (u). The adjacent
information management unit 404 creates the adjacent information
management table 405, using the type 0 adjacent node list and the type 1
adjacent node list calculated by the type 0 adjacent calculation unit 402
and the type 1 adjacent calculation unit 403. In the adjacent information
management table 405, the type 0 adjacent node list and the type 1
adjacent node list are stored for each ID (node in FIG. 2) of the
information terminal 102.

[0052] If the adjacent management unit 115 of an information terminal 102
queries on the adjacent information, the adjacent information
corresponding to the ID of this information terminal 102 can be acquired
and transmitted with reference to the adjacent information management
table 405. The adjacent management unit 115 can maintain the adjacent
information in the latest state by constantly querying the management
server 101 on the adjacent information, or receiving an adjacent
information update instruction from the management server 101.

[0053] Normally k0 is a value that is sufficient for all the network nodes
to reach any node via a link. The type 0 is a local link that connects
nodes within a short distance, and type 1 is a shortcut link that
directly connects with a distant adjacent node without going through the
local link. By creating these two types of links, as mentioned above, all
the nodes can reach any node by tracking the links, and all the nodes can
be reached with the similar number of hops regardless of the distance
scale of a node.

[0054] Now a function of the messaging unit 116 will be described with
reference to FIG. 5 and FIG. 6. The messaging unit 116 constitutes an
inter-user message transfer platform for propagating a new message
created by a user who operates the information terminal 102 and a message
created by other users via the network.

[0055] First a case when a user who operates the information terminal 102
creates a new message will be described. The user inputs information via
the interface unit 114, and the information management unit 112 creates a
message based on this input information. This message contains detailed
creation information in addition to such meta-information as a message
ID, ID information on the information terminal 102, and a message
creation date and time.

[0057] The message box 502 is an information container opened to other
terminals 102, and other terminals 102 can freely acquire information.
The message box 502 is constructed as a finite buffer, and secures a
buffer area for each of the predetermined categories. In the case of the
example in FIG. 5, only meta-information of the message is shown in the
message 503, but a message category ID and a creation time may be
contained in the meta-information. In this example, the buffer length of
the message box 502 is four, and one message storage area is assigned to
each message category. In other words, according to this example,
messages for four categories can be stored. The message management unit
501 stores new information with priority for each category, and if the
message size exceeds the buffer size, only newer information (information
of which creation date and time is later) is saved if the messages have a
same category ID.

[0058] If a message with a new category ID is input when the buffer is
completely full, the inputted message is compared with the oldest
information stored in the buffer, and if the inputted message is newer,
the inputted message overwrites the oldest information. Then if a message
newly created in the information terminal 102 is inputted, this message
is always newer than the other message stored in the buffer, so if the
buffer is completely full, the new message overwrites the oldest message,
and the old information is discarded. A new message is posted in this
way.

[0059] Now a method for forwarding a message will be described. First the
message management unit 501 periodically acquires the adjacent
information terminal list from the adjacent management unit 115, selects
one or more adjacent information terminal(s) from the list, and acquires
a message from the message box of the terminal(s). The selection method
can be random or sequential based on a round robin approach.

[0060] Then the acquired message and the current message box 502 are
compared, and the new message is stored in the message box 502 according
to the above mentioned rule. The message is forwarded by the other
information terminals 102, which refer to this information terminal 102,
performing the same operation.

[0061]FIG. 6 depicts a state of a message being forwarded using a simple
example. In the example in FIG. 6, a message is propagated in the nodes
601, 602, 603, 604 and 605. Each node has two adjacent nodes
respectively, and the size of the message box is assumed to be 1 (only
one message can be stored) to simplify description. Each node
sequentially refers to only one adjacent message box each time
round-robin.

[0062] Now it is assumed that an event 621 is generated, and the node 601
creates a message 610 and posts the message in the message box. After a
unit of time elapses, the node 602 acquires the message 610 from the
message box of the node 601, and posts the message 610 in the message box
of the node 602 to open the message 610 to the public. After another unit
of time elapses, the node 603 acquires the message 610 from the node 602.
Here it is assumed that the node 604 has already browsed the message
boxes of adjacent nodes other than the node 602. The node 602 refers to
the node 605, but node 602 does nothing since the message box of the node
605 is empty.

[0063] After another unit of time elapses, the node 604 acquires the
message 610 from the message box of the node 602, but node 602 does
nothing since the node 602 has already referred to the message box of the
node 601 and has already acquired the message 610. In the same manner,
the node 603 does nothing, since the node 603 has already acquired the
message 610 in the message box of the node 602. It is assumed that the
node 605 created a message 611 on a new event 622, and posted this
message 611 in the message box during this time. Then after another unit
of time elapses, the node 602 refers to the message box of the node 605,
knows that the new message 611 is posted, and overwrites the message 610
with the message 611. Hereafter the message 611 is sequentially
transferred to the downstream nodes 603 and 604.

[0064] A message created by each information terminal 102 propagates
through the network using this message transfer mechanism. TTL (Time To
Live) may be set for a message so that a message after a predetermined
time has elapsed or a transferred message that hopped the predetermined
number of nodes or more is automatically discarded.

[0065] Now the operation when each information terminal 102 executes an
action based on the message information will be described with reference
to the flow chart in FIG. 7. The information management unit 112 executes
a predetermined action based on new information acquired by the messaging
unit 116. An example of the "action" which is referred to here is to
display information to a user and enter a standby state to wait for an
input or some action by the user, or to automatically perform certain
information processing, and this action is executed by the action
algorithm unit 117.

[0066] To simply description, here it is assumed that an action to display
the summary information of a message to the user is predetermined, but
the present invention is not limited to this mode. For example, it is
also possible to install a more advanced information processing, such as
displaying information to a user only when information the user is
interested in or information on a predetermined category is input.

[0067] If the information terminal 102 is started up, the information
terminal 102 enters a new message standby state (step S701). Then in step
S702 (action start condition determination), it is determined whether a
new message was inputted. If it is determined in step S702 that a new
message was not inputted, processing returns to step S701. If it is
determined in step S702 that a new message was inputted, then processing
advances to step S703.

[0068] In step S703, the action algorithm unit 117 is called up and the
summary information is displayed to the user, and processing advances to
step S704. In step S704, it is determined whether a predetermined action
end condition is satisfied. Here an action end condition is information
inputted by the user pressing an OK button, or generation of a
predetermined time of a time out event. If this end condition is
satisfied, processing returns to step S701, and enters the standby state
again to wait for an input of a new message. The action algorithm unit
117 need not be called up for an information terminal 102, which only
performs messaging.

[0069] Because of the above described functions, the user of the
information terminal 102 can acquire information in real-time which is
posted by another user and which propagates the network, regardless of
the state of the user, and the user can respond to the posted information
with an action. Here the information terminal 102 according to this
embodiment excels in real-time characteristics because the above
mentioned network structure is created, and links are created with nodes
having similar probability regardless of the distance scale, which means
that new information can be acquired quickly regardless of the state
(place), without depending on the state (e.g. current position) of the
user who created the new information and the state of the node that
received the information, and a desired action can be taken based on this
information.

[0070] Therefore according to the present embodiment, a network structure
is created so that regardless of the distance scale of the information
terminal 102, which transmits detailed information on a search event that
is dynamically created, from the searcher, the searcher can acquire
information at a predetermined probability, and the coordinated
forwarding of the detailed information message is performed on this
network. As a result, regardless where the searcher is positioned on the
network with respect to an arbitrary search event, the searcher can
efficiently acquire a message on the search event.

[0071] Furthermore, only one or a small number of limited adjacent
information terminal(s) 102 can transfer a message at the same time,
hence the consumption of network resources are less than that of
broadcasting. In each information terminal 102, old information is
overwritten by new information and is discarded, so the buffer size of
each information terminal 102 can be small.

[0072] According to this embodiment, an information terminal moves or
changes the internal state of the terminal using acquired information as
a clue, so as to gradually approach or zero in on the state of
information of interest, and improves the accuracy of the information
under search by repeating actions based on information newly received
during this movement or change.

[0073] In this embodiment, the management server 101 is used to calculate
or manage the network configuration among the information terminals, but
a desired network structure may also be created using a distributed
method without using the management server 101. For example, an initial
adjacent list is provided to the information terminal 102 and the
information terminals 102 sequentially update the adjacent list while
communicating and exchanging information with the current adjacent
information terminals.

[0074] The number of type 0 adjacent nodes and the number of type 1
adjacent nodes of an information terminal 102 may be the same, or a ratio
of the adjacent nodes of one of the types may be higher than the other.
The ratio of the numbers may be changed as time elapses. For example, a
ratio of the type 1 adjacent nodes may be set higher in the beginning, in
order to collect messages from nodes over a wide range, and a ratio of
the type 0 adjacent nodes may be increased so that messages from nodes in
a close distance can be efficiently acquired after some elapse of time.

EXAMPLES

Example 1

[0075] Example 1 of the present invention will now be described.

[0076] In the example in FIG. 8, the information terminals are smart
phones 811, 812 and 813, and each of a plurality of users distributed in
the subject field 802 have their own smart phone. Here a case when target
801, which exists in a field 802, moves dynamically, and a tracker 803
searches for the target 801 using messages acquired by the coordinated
information collection system of the present invention, will be
described.

[0077] Users distributed in the field 802 move merely randomly without
knowing the location of the unnamed tracker 803, and if the target 801
enters within a certain radius range, each user posts this target witness
information in the message box, messaging the time and place the target
was witnessed. Each of the other users acquires only new information out
of the target witness information of the adjacent message boxes, and
posts the acquired information in the message box of this user. By the
link of this message transfer, the tracker 803 collects the target
witness information and searches for the target 801. Tracking succeeds
when the target 801 enters a certain radius range of the tracker 803. The
message transfer is automatically and periodically performed among the
smart phones of the users, and a message of a predetermined or longer
time that has elapsed since reception is discarded by an appropriate TTL.

[0078] All users periodically notify their respective current position to
the management server 814, and acquire new adjacent node information
calculated by the network configuration management unit 123 at each
notification. In this example, it is assumed that the tracker 803 can
move faster than the target 801.

[0079] Now it is assumed that tracking began from an arbitrary position.
Each current position [of the smart phones] is notified to the management
server 814, a list of IP addresses, as the adjacent information, is
notified to all the smart phones, and the IP addresses of the adjacent
smart phones are registered in each smart phone. A user who happens to be
near a target 801 at each timing posts a target witness message with an
appropriate probability. For example, it is assumed that a user of a
smart phone 811 posted a target witness information as a message 815.
Then at a next timing, the message 815 is propagated to the smart phone
812, and at a next timing, the message 815 is propagated to the smart
phone 813 of the tracker 803. The tracker 803 approaches the target 801
by moving to the target witness position as stated in the message 815. In
this case the transfer delay for this message is 2.

[0080] Since there is a delay, from the witness 804 witnessing the target
801 until the tracker 803 receiving the message 815 and moving to the
target position, and since the target is also moving during this same
time, the tracker 803 cannot always quickly catch up with the target 801.

[0081]FIG. 9 is a diagram depicting a state of tracking in detail, from
time t, when the target is witnessed to time when the target is witnessed
again, and FIG. 10 is a flow chart depicting a tracking algorithm of the
tracker. Here the action algorithm provided in the information terminal
of the tracker has a function to display the latest received messages for
the tracker in sequence from the most recent, and based on this
information, the tracker tracks the target in the sequence shown in FIG.
10.

[0082] The tracker is in message standby state (step S1001) at time
ti. A user near the target witnesses the target and posts the target
witness information (event 901). The distance between the target and the
tracker in this case is assumed to be x [ti]. The message, including
the target witness information, arrives to the tracker at message
transfer delay τF (event 902). If the moving velocity of the
target is v, then the target will have advanced by vτF when the
tracker receives the message.

[0083] The tracker who received the message determines whether a new
message was received in step S1002, and because in this case a message
was received, processing advances to step S1003. In step S1003, the
tracker advances to the place stated in the target witness information at
velocity u. It takes τ=x[τi]/u until the tracker reaches the
place stated in the target witness information (event 903). This means
that the target advances further by Vτ during this time. As a result,
the distance between the tracker and the target when the event 903 is
generated is vτF+Vτ at the maximum.

[0084] In step S1004, it is determined whether the target entered the
scope range δ of the tracker. Tracking is a success if the target
is in the scope range δ. If the target is not in the scope range
δ, the tracker stops, returns to step S1001, and waits to receive
the next message.

[0085] If the time when the next target witness event 904 is generated is
ti+1=ti+τW, the same operation is repeated with
x[ti+1] as a distance between the target and the current position of
the tracker, but if x[ti+1]-x [ti]<0, then the distance from
the target decreases with certainty, and eventually the condition in step
S1004 is satisfied.

[0086] In this example, the interval τw between the witness
events that occur is long, but if the witness events are generated more
frequently, the tracker may acquire a new witness message while moving.
In this case, the tracker who reached a target witness spotting can
immediately head for the next target witness spotting, therefore tracking
success probability increases. The goal may be changed to the latest
target witness spotting while moving.

[0087] According to the coordinated information collection system of the
present invention, if the message transfer platform is created, a
shortcut link creation probability, with respect to a distance scale,
becomes approximately the same, so if a predetermined condition (e.g.
velocity ratio of the target and the tracker with respect to a given
network scale, scope range, amount of transfer delay) is satisfied, the
target witness information can be efficiently acquired without depending
on the initial positions of the tracker and the target. Whereas in the
case of a cluster network created only with local links, without using
shortcut links, a probability of receiving target witness information is
low when the tracker and the target are distant. If shortcut links are
created randomly, on the other hand, a probability of creating a shortcut
link with a user at a long distance scale increases, and a probability of
receiving a message decreases when this distance between the tracker and
the target becomes short, hence the unexpected number of steps until
tracking success increases.

Example 2

[0088] Example 2 of the present invention will now be described with
reference to FIG. 11.

[0089] If the coordinated information collection system of the present
invention is used, a user, who received witness information on a suspect
while moving from a departure place to a destination, can change their
route, and select a safe route that maintains at least a predetermined
distance from the suspect while sequentially receiving witness
information. In the case of an example in FIG. 11, a user 1100 is heading
for a destination 1102 from a departure place 1101, and a user 1110 is
heading for a destination 1112 from a departure place 1111, both
attempting to take the shortest distance.

[0090] In this field, a plurality of suspects exist and are moving at
random. A suspect can cause harm to a general user who enters a
predetermined range from this individual with certain probability. In
Example 2, the "internal state" of the user refers to a physical place,
for example, and users form a network using physical places, and if a
user happens to be near a suspect and witnesses that individual, this
user posts a message, on the coordinated information collection system
including the time when the suspect was witnessed and what this suspect
looked like.

[0091] If this message is received, each user checks whether the position
where this suspect was witnessed is within a predetermined distance from
a line connecting the current position of the user and the destination,
and if so, the user changes direction at a proper angle to take a detour
route. For example, it is assumed that the user 1100, who is moving in
the traveling direction 1103, received witness information on suspect
1130. In this case, the user 1100 changes their current traveling
direction to the traveling direction 1105 by making a turn at detour
angle 1104. If a new witness information on a suspect is received before
reaching a place connected with the destination 1102 on a straight line,
the user 1100 takes a detour route again in the same manner, correcting
their direction at a different angle, so as to reach the destination in a
shortest distance.

[0092] By using the coordinated information collection system of the
present invention, a user with good will, such as a neighbor or an
individual interested in maintaining public safety, can simply post
witness information about a suspect on the system, whereby the message
propagates through the network, and an unspecified user interested in the
message (e.g. a user traveling on a route on which the witness position
of the suspect exists) can receive the message, and avoid danger in
advance.

[0093] A user who relays the information simply receives messages from
adjacent nodes, which are automatically and periodically updated, and
buffers these messages if the terminal of the user has resources,
therefore consumption of the network resources and the computing
resources are kept low, and this user need not actively coordinate with a
user who is interested in acquiring the message.

[0094] In the case of many network structures other than the embodiments
of the present invention, a probability of receiving a message largely
depends on the distance of a place where the message is posted and a
current position of the user. But according to the present invention, the
dependence on this distance scale can be kept to a minimum. Another
characteristic of the present invention is that the user who posts
information need not have concern for reliability of this information.
This is because it is essentially the reception side that determines
message reliability. For example, if there are many other users who
posted a message on a suspect, statistically the individual that many
determined as suspicious has a high probability of being suspicious, and
the reception side can statistically evaluate reliability based on a
number of users who transmitted a message. For example, the user can
regard information as highly reliable if the number of messages on a
suspect reaches the predetermined number or more within a predetermined
area in a same time period.

[0095] Furthermore, another user 1110 heading to a similar destination
among the users receiving this information naturally takes a similar
route to avoid danger by similar processing, which means that users who
received the information tend to share a same route. For example, the
user 1100 and the user 1110 in FIG. 11 take the route 1106 and the route
1113 respectively, which share some area. Generally a suspect tends to
avoid an area where individuals gather, or has difficulty in performing
harmful action in such an area, therefore safety is increased.

Example 3

[0096] Example 3 of the present invention will now be described.

[0097] Among Internet web pages, there are many pages hosting computer
viruses or which include content harmful to children. Companies who
develop security software monitor these pages, and provide software-based
functions to block such pages in advance, but essentially the information
is posted after a harmful web page is discovered and confirmed by
monitoring and reporting, therefore some delay is generated until the
security software program installed on each computer downloads the
functions that enable blocking.

[0098] Furthermore computer viruses and harmful pages change dynamically,
so it is difficult to follow up the new generation and modification of
viruses and harmful pages in real-time. Also the only available remedy at
the moment to control Web sites, which are not necessarily harmful but
which parents regard as inappropriate for their children, is for ISPs to
block these sites when the user registers for Internet service.

[0099] If the coordinated information collection system of the present
invention is used, harmful web page information, posted by a user who
happens to browse such a Web site or a user who acquired information on
such a Web site, can be acquired, which makes it possible to quickly
launch countermeasures to avoid accessing the site.

[0100] A case of applying the present invention to a parental control
program, which automatically blocks harmful sites for children, is
considered. A plurality of adults post information on a site, which
includes the content that is regarded as harmful for children. In this
example, the "internal state" of the user refers to a vector expressing a
characteristic of a Web site currently being browsed or a past record
thereof. This vector is a vector created based on the frequency of major
words used on the site, for example, and the distance between internal
states can be defined based on cosine similarity of the vectors.

[0101] A network is dynamically constructed using the internal states, and
each user posts a time when a harmful site was browsed and the URL
thereof. This information is propagated to various users via the network.
The above mentioned parental control program has criteria to determine
reliability of the degree of harm of the information, and a definition of
the countermeasures to take (e.g. blocking, issuing a warning, logging
information and e-mailing it to parents), and constantly monitors the
current internal state of a child-user based on the current Web browsing
record. Then a predetermined action is taken if necessary by comparing
this internal state and the harmful site information in the received
message. For example, access to the harmful site stated in the harmful
site information, which was regarded as reliable, is blocked, or access
to the Web site is disabled when the internal state approaches the site
at a predetermined distance.

[0102] A newly created web page can be found by using the same structure.
For example, it is assumed that a user posted the URL of an interesting
web page on the network of the coordinated information collection system
of the present invention. If there are many such users, many messages on
this web page propagate, and a user who receives these messages can know
about the web page that they are interested in, and what is popular among
many users.

[0103] By sequentially approaching the target page in the same manner as
the tracking in Example 1, a page currently being browsed can be
efficiently moved closer to the page. Here a filtering function, to
display only messages which contain information of interest to the user,
may be included in the program.

[0104] As described above, the present invention can be applied to an
application to efficiently collect information with high real-time
characteristics, such as events generated in a dynamically changing
state. In particular, the present invention can be applied to an
application to search and track a dynamically moving target, such as a
mobile game and a lost child. The present invention could also be applied
to crime prevention and security in terms of avoiding danger. The present
invention can also be applied to support users in order to efficiently
access popular content, information and web pages.

[0105] This application claims priority based on Japanese Patent
Application No. 2010-204609 filed on Sep. 13, 2010, and includes all
disclosures thereof.

[0106] While the present invention has been described with reference to
the embodiments, the embodiments are not intended to limit the invention.
Configuration and details described in the present invention can be
modified in various ways by those skilled in the art within the scope of
the present invention.

[0107] Part or all of the embodiments can be described according to the
following additions, but the present invention is not limited to these
descriptions. (Addition 1) A coordinated information collection system
comprising a management server and a plurality of information terminals
which are connected via a communication network, wherein the management
server has:

[0108] a terminal state management unit that manages state information
transmitted from the information terminals and including information on
an information terminal and a user associated with each of the
information terminals; and

[0109] a network configuration management unit that selects adjacent
information terminals of the information terminals, based on the state
information of each of the information terminals managed by the terminal
state management unit, and calculates a connection link, which is a
network for interconnecting the adjacent information terminals, and

[0110] the information terminals respectively have:

[0111] an internal state management unit that manages the state
information of the information terminal;

[0112] an adjacent management unit that manages information on adjacent
information terminals selected by the network configuration management
unit; and

[0113] a messaging unit that stores a message acquired from an adjacent
information terminal via the connection link and a message inputted by
the user in a message box opened to other information terminals, and
manages these messages, and wherein

[0114] the network configuration management unit calculates a degree of
dissimilarity among information terminals based on the state information
of each information terminal, and calculates a first type connection link
that creates a connection link sequentially from an information terminal
having a lowest degree of dissimilarity, and a second type connection
link which is created stochastically based on the degree of
dissimilarity.

[0115] (Addition 2)

[0116] The coordinated information collection system according to Addition
1, further comprising: an information management unit that analyzes a
message acquired from another information terminal via the connection
link; and an action algorithm unit that executes a predetermined
processing using a message analysis result by the information management
unit.

[0117] (Addition 3)

[0118] The coordinated information collection system according to Addition
1, wherein the internal state management unit acquires and manages a
current position measured by GPS as the state information, and the degree
of dissimilarity is calculated from relative positions among information
terminals based on the current positions.

[0119] (Addition 4)

[0120] The coordinated information collection system according to Addition
1, wherein the second type connection link is generated with a similar
probability regardless the degree of dissimilarity, and when the degree
of dissimilarity with an information terminal other than an information
terminal connected via the first type connection link is r, a probability
that the second type connection link is created with this information
terminal is in proportion to the -αth power of r (α is a
positive number).

[0121] (Addition 5)

[0122] The coordinated information collection system according to Addition
1, wherein the messaging unit sequentially stores a new message, which is
periodically acquired via the first type connection link or the second
type connection link, in the message box, then if the storage capacity of
the message box reaches the upper limit, the messaging unit discards the
oldest message among the messages on a same target as a new message from
among the stored messages, and when there are no messages on a same
target as a new message, the messaging unit discards the oldest message
among all the stored messages, and stores the new message, and discards
as well a message of which storage period is not less than a
predetermined time or a message acquired via the predetermined number or
more information terminals.

[0123] (Addition 6)

[0124] The coordinated information collection system according to Addition
2, wherein the message is on target witness information, including a
position where a target has been witnessed, and the action algorithm unit
outputs a message of which generation time is the latest, until a
distance between the current terminal and the target becomes a
predetermined distance or less.

[0125] (Addition 7)

[0126] The coordinated information collection system according to Addition
2, wherein the message is on target witness information, including a
position where the target has been witnessed, and the action algorithm
unit outputs a message of which generation time is the latest until the
current terminal arrives at the destination.

[0127] (Addition 8)

[0128] The coordinated information collection system according to Addition
2, wherein the state information is a value that indicates content
characteristics of a web page which the user is browsing or has browsed
using the information terminal, the degree of dissimilarity reflects a
degree of dissimilarity of content characteristics of any two web pages,
the message contains information on the content of a web page, and the
action algorithm unit blocks accessing a harmful web page according to
predetermined conditions, using a message analysis result.

[0129] (Addition 9)

[0130] A coordinated information collection method used for a coordinated
information collection system having a management server and a plurality
of information terminals which are connected via a communication network,
wherein

[0131] the management server manages state information, associated with
each of the information terminals and transmitted from the information
terminal, and selects adjacent information terminals of each information
terminal based on the state information of each of the information
terminals, and calculates a connection link, which is a network for
interconnecting adjacent information terminals, and

[0132] the information terminal stores a message acquired from an adjacent
information terminal via the connection link, and a message inputted by
the user in a message box opened to other information terminals, and
manages these messages, and

[0133] the connection link includes a first type connection link that
creates a connection link sequentially from an information terminal
having a lowest degree of dissimilarity, among information terminals,
which is calculated based on the state information of each information
terminal, and a second type connection link which is created
stochastically based on the degree of dissimilarity.

[0134] (Addition 10)

[0135] A program for causing a computer to function as:

[0136] a terminal state management unit that manages state information
transmitted from a plurality of information terminals and including
information on an information terminal and a user associated with each of
the information terminals; and

[0137] a network configuration management unit that selects adjacent
information terminals of the information terminals, based on the state
information of each of the information terminals managed by the terminal
state management unit, and calculates a connection link, which is a
network for interconnecting the adjacent information terminals, wherein

[0138] the network configuration management unit calculates a degree of
dissimilarity among information terminals based on the state information
of each of the information terminals, and calculates a first type
connection link that creates a connection link sequentially from an
information terminal having a lowest degree of dissimilarity, and a
second type connection link which is created stochastically based on the
degree of dissimilarity.

[0139] The present invention is suitable for applications to efficiently
collect information with high real-time characteristics, such as events
generated in a dynamically changing state.